Maturity and acceptability of early-picked Granny Smith apples for export

Abstract

This study examined the rate of maturation of Granny Smith apples on the trees in several districts of New South Wales and the relationship between picking dates, starch content of the fruit at picking and its palatability after simulated export conditions. Starch-iodine number as a measure of starch content is a useful index of fruit maturity. The starch content fell with time on the tree; there were differences in rate and level between early, mid-season, and late districts. A starch level of 3 gave fruit of acceptable maturity for immediate eating. A critical minimum starch level of 1 ensured that fruit would reach a sufficient level of maturity for general consumer acceptability after simulated export storage. Measurement of starch-iodine number for individual orchards is recommended as a basis for determining picking dates for fruit for export, assuming a critical minimum starch-iodine number of 1.